Boost your diet with foods rich in probiotics and prebiotics

If your digestion and immune system seem a bit off, it may be time to boost probiotics in your body—those beneficial bacteria that promote overall health. Here are foods to look for and ways to supplement with probiotics for yourself and kids.

Lately, your digestion feels off; in fact, you've caught a few more colds than usual and your overall vitality seems a bit compromised. Must be time to detox, right? The truth is that solely focusing on flushing toxins from your digestive system is a bit like cleaning the pool filters but forgetting to add chlorine.

"We tend to think of gut maintenance as only removing poisons and neglect to think of what we need to add to our system to keep it healthy," says Gary Huffnagle, PhD, professor of internal medicine, microbiology, and immunology at the University of Michigan Medical Center in Ann Arbor, and co-author of The Probiotics Revolution (Bantam, 2007). That's where probiotics (or friendly bacteria) come in.

Foods high in probiotics

Aged cheese

Beer (microbrews)

Cottage cheese (look for bacterial strains in ingredient list)

Kefir

Kimchi

Miso

Pickled ginger

Pickles (brine-cured, without vinegar)

Sauerkraut

Shoyu

Tamari

Tempeh

Tofu

Wine

Yogurt

At any given time, there are about 100 trillion bacterial microbes living inside your body — enough microscopic beings to fill up a quart jar — most of which reside in the digestive tract. “The digestive system is like a rainforest — teeming with life,” explains Elizabeth Lipski, PhD, CCN, a nutritionist in private practice in North Carolina and author of Digestive Wellness (McGraw-Hill, 1995).

When friendly bacteria levels outnumber the bad, the body is in stasis. But the by-products of modern life often throw this delicate balance out of whack. “The combination of a typical Western diet, the high stress levels of modern life, and an over-reliance on antibiotics is the equivalent of clear-cutting parts of our internal ecology,” Lipski explains. In other words, if you're a typical member of Western society, it's likely time to reforest your internal landscape.

There are thousands of probiotic strains, or friendly flora, found naturally in everything from breast milk to pickles. When ingested they actively promote overall health in many ways. Probiotics take up room and resources in the digestive tract and make it inhospitable to unfriendly microbes. They encourage regularity: In a 2006 Spanish study, daily probiotic consumption increased the frequency and volume of bowel movements, and a 2007 study found that the probiotic strain Lactobacillus rhamnosus GG greatly reduced acute diarrhea in children. Good bacteria also manufacture a range of B vitamins, which the body cannot create or store on its own and which offset the effects of stress; vitamin K, which bolsters bone density; and enzymes that aid metabolism.

And the benefits of probiotics extend well beyond the realm of nutrition and digestion. “Because the digestive system is our first line of defense against harmful bacteria carried in through food, drink, or air, probiotics help the immune system function correctly,” Huffnagle says. In recent studies, probiotics reduced the duration and severity of colds, cut down recurrences of eczema outbreaks, increased the effectiveness of the flu vaccine, and decreased the risk of diabetes.

If you suffer from constipation or diarrhea, frequent colds, yeast infections, or inflammatory or autoimmune conditions (such as IBS, allergies, asthma, or rheumatoid arthritis), it's likely your probiotic levels need a boost. But even if you're relatively healthy, increasing your intake of probiotics through diet and supplements tips the balance in your favor.

Revamp your diet

Natural sources of probiotics include fermented foods, such as sauerkraut, or cultured foods, such as yogurt. Pay attention to your intake of prebiotics, too. Prebiotics are probiotics' favorite foods and help them thrive. But maintaining a healthy gut requires more than just eating a cup of yogurt with berries now and then. “In order to keep your bacteria levels in balance with diet alone, you have to commit to eating fermented and cultured foods every day,” Lipski says. While that may be possible during quiet times, when you can eat the majority of your meals at home, one spurt of busyness can derail your efforts. Luckily, probiotics come in easy-to-take supplements (for help choosing the right one, see "Probiotic shopping tips").

What are prebiotics?

Like many health-boosting nutrients, probiotics don't function in isolation. They require food, or “prebiotics” — including oligosaccharides and inulin (forms of soluble fiber found in some grains, fruits, and vegetables) and phenols (antioxidant compounds also found in plant foods). Eating more of the following prebiotic-rich foods can help support your probiotic numbers.

Asparagus

Jerusalem artichokes

Bananas

Leeks

Barley

Oats

Beans

Onions

Beer (microbrews)

Peanuts

Berries

Peas

Cherries

Red wine

Dark chocolate

Soybeans

Eggplant

Tea

Garlic

Whole rye

Herbs, fresh

Whole wheat

Supplement well

“Taking probiotic supplements is like taking out an insurance policy — it protects you during the tough times,” Huffnagle says. To get the most mileage out of your supplement, Huffnagle suggests opening the pill casing and sprinkling the contents into a beverage or onto food so that the flora are introduced to your mouth and esophagus — important links in the digestive chain — as well as your stomach and intestines. Just be sure the food isn't scorching hot — anything above warm may kill the microbes.

Culture your kids

“Giving kids probiotic supplements helps set up their gut and immune health for life,” Lispki says. “It also counteracts the many rounds of antibiotics our kids are exposed to these days.” Here's her advice for babies up to a year old: Make a paste of Bifidobacteria infantis — typically the only probiotic babies are exposed to until they consume a wider variety of solid foods — and place it on their tongues. If you are breastfeeding, you can also simply take one or two capsules of the supplement yourself. For kids ages 1 to 4, try a supplement that contains Bifidobacteria infantis and Lactobacillus acidophilus, another common type of probiotic. “You can sprinkle it on their food,” Lipski suggests. Once kids reach age 4, they can take the same supplement you do.

Note: If you or your child begin taking supplements and experience an up-tick in digestive upset, it's likely a result of the bad bacteria dying off and releasing their toxins. Instead of stopping supplements altogether, Huffnagle recommends decreasing your dose and then gradually increasing it over time. “There's no evidence that you can overdo it,” he says.

Kate Hanley is a Brooklyn-based writer and the founder of www.msmindbody.com. She eats more yogurt, pickles, and kimchi since writing this article.

Probiotic shopping tips

BRAND
Some manufacturers do a better job of delivering viable microbes (identified on the label as CFU, short for colony-forming units) than others. Gary Huffnagle, PhD, a professor at the University of Michigan Medical Center, recommends Align, Culturelle, Florastor, Jarrow, and Theralac.

FREEZE-DRIED
Freeze-drying, which removes all water from the microbes, makes them more likely to survive in pill form. When you take the supplement, the fluid in your digestive tract reanimates the bacteria.

REFRIGERATED
Although some high-quality supplements don't require refrigeration, most do. Lower temperatures increase the length of time microbes can survive.

MULTIPLE STRAINS
Look for a supplement that contains different species of bacteria, such as Lactobacillus and Bifidobacteria. “You want a variety in your probiotics just as you want variety in your diet,” says nutritionist Elizabeth Lipski, PhD, CCN, author of Digestive Wellness (McGraw-Hill, 1995). And look for a different formulation the next time you shop for supplements. “I generally have people take one supplement for a while and then switch so they get exposed to a wide range of benefits.”

OTHER INGREDIENTS
Because probiotics need food as soon as they reanimate, a supplement that contains a prebiotic, such as inulin, can improve the flora's chances of surviving in your digestive system.

DOSE
“For the average, healthy person, a dose between 5-10 billion microorganisms is protective and preventive, even if you take the supplements only a few times a week. If you've been on antibiotics or are recovering from illness, aim for 30 billion,” Huffnagle recommends. Look for supplements that clearly state each dose's CFU. Avoid those that list ingredients only by weight.

EXPIRATION DATE
Because probiotics contain live microbes, they won't remain viable forever. Make sure to purchase in quantities that will enable you to finish the supplements before the expiration date.
— K.H.